Question: Is performing a voluntary salat more important than performing a qada salat? Is there any difference between not performing salat by considering it unimportant and missing it due to an excuse?
ANSWER
[To carry out a salat within its prescribed time period is called adaa. To carry it out after its prescribed time has ended is called qada. Throughout this article, we will use the verb make up to mean to do qada of a salat.]

Of course, there is a big difference between these two. One becomes a disbeliever (kafir) if one does not perform salat by considering it unimportant. Missing a salat due to an excuse, such as sleeping and forgetting, is called fawt, and a salat missed due to such a reason is called faita. Faita salat is a salat that it is not a sin to miss. For this reason, it is not a sin to delay performing faita salats as much as to perform voluntary (nafila) salats, such as Salat ad-Duha and Tahiyyat-ul-Masjid.

"It is a major sin not to perform a fard [obligatory] salat without an excuse at its prescribed time. It is necessary to make it up right away. With the exception of the time that one may reserve for essential duties, it is a major sin, too, to delay making it up" (Bariqa).

As performing a voluntary (nafila) salat is not an essential duty, it is a sin in all of the four madhhabs to delay making up an omitted salat by performing a voluntary salat. If one, when facing the enemy, does not perform a fard salat though it is possible to perform it, skipping it is equivalent to 700 major sins. (Umdat-ul-Islam, Jami'-ul-Fatawa)

"It is a major sin to omit a fard salat out of laziness, in spite of the fact that one cares about it" (Durr-ul-Mukhtar, Jawhara).

It is disbelief (kufr) not to know it a duty to perform salat and to make light of it. It is stated in hadith-i sharifs:

(A person who omits a salat deliberately becomes a disbeliever.) [Tabarani]

(The thing that separates disbelief from faith is to omit salat.) [Tirmidhi]

(Salat means faith. A person who performs salat by observing its time and other conditions is a Believer.) [Ibn Najjar]

The best deed is fard salats performed at their due times. It is stated in hadith-i sharifs:

(Allahu ta'ala is pleased with him who performs salat right away when the time for it starts. As for the one performing it at the time when it is quite close to the end of the time for it, He forgives him.) [Tirmidhi]

(My Rabb promised that He would not inflict torment on a person performing salats properly at their due times.) [Hakim]

(The first act of worship a person will be questioned about on the Day of Resurrection will be salat. If his salats are found correct, his other deeds will be accepted, too. If they are not found correct, none of his deeds will be accepted.) [Tabarani]

When a Sahabi asked our Master the Prophet the deed that would take him to Paradise, he answered, "A person who does not associate partners with Allah, who performs fard salats, who pays zakat, and who fasts in the month of Ramadan will go to Paradise." That person said, "By Allah, I will do no more than these." Our Master the Prophet stated, "Let him who wants to see a person of Paradise look at him" (Bukhari). Although the Sahabi swore that he would not perform voluntary acts of worship, our Master the Prophet stated, "He will go to Paradise." This means that offering voluntary acts of worship is not essential. Islamic scholars said that voluntary acts of worship would compensate the deficiencies in one's obligatory acts of worship.

"The sunnat salat of Salat al-Fajr is very rewarding. However, there is no punishment declared even for a person who omits the sunnat salat of Salat al-Fajr" (Tahtawi).

A hadith-i sharif reported by Muslim says, "The most excellent salat after the obligatory ones is the one performed at night [Salat at-Tahajjud]." If one does not perform Salat at-Tahajjud even once in one's lifetime, no punishment will be inflicted on one because it is a voluntary salat. Hadrat Imam-i Rabbani states:

"When compared to those acts of worships that are fard, voluntary acts of worship are of no value. They are not even a drop of water compared with an ocean. The accursed Satan is deceiving Muslims by misrepresenting obligatory acts of worship as insignificant. He is misleading them towards voluntary acts of worship. He is preventing them from paying zakat and is misrepresenting non-obligatory alms as beautiful. In fact, to give one gold coin to a poor with the intention of zakat is much more thawab than giving a hundred thousand gold coins as alms" (Letter 29).

Hadrat Abd al-Haqq ad-Dahlawi, one of the scholars of the Hanafi Madhhab, states the following in his commentary on Futuh-ul-Ghayb:
(If a person has a missed fard salat, his performing voluntary salat is like [the case of] a pregnant woman who has a miscarriage when she is about to give birth to the baby. The woman cannot be said to be pregnant, nor can she be called a mother anymore. So is this person. Unless he makes up his missed salats, Allahu ta’ala will not accept his voluntary salats.) This hadith-i sharif, which is written in the book Zahira-i Fiqh as well, proves that the sunnat salats of a person who has salats to make up will not be accepted because sunnat salats, too, are voluntary salats.

Question: Is it appropriate to perform a qada salat after each fard salat?
ANSWER
Just as it is a major sin not to perform a fard salat without an excuse at its due time, so it is a major sin to delay making it up without an excuse. This very grave sin becomes double as each free time that is long enough to perform salat passes because it is fard also to make up qada salats in your free time as soon as possible. To get rid of this terrible sin, which cannot be calculated or measured, and for escaping its torment, one must make every effort to make up one's qada salats as soon as possible. With the exception of the time that one may reserve for earning one’s sustenance and the sustenance of those who it is wajib for one to support, it is not permissible for one to delay qada salats for any other reason.

Question: In the books I wrote, it is written, "If one has salats to make up, it is haram for one to perform sunnat and voluntary salats according to the madhabs of Shafi'i, Maliki, and Hanbali." Why is it haram to perform sunnat and voluntary salats? Can performing salat be haram? Secondly, it is stated in hadith-i sharifs, "A person who performs a salat after its due time is over will stay in Hell for 80 huqba" and "It is a major sin to combine two fard salats." Do these two hadiths not make it haram to do qada of a salat?
ANSWER
It is not haram for a person who has salats to make up to perform sunnat and voluntary salats. What is haram is to delay performing qada salat without an excuse. When performing a sunnat or a voluntary salat, one is considered to be delaying one's qada salats. For this reason, it is stated that it is haram to perform sunnat or voluntary salats if one has salats to make up. That is, it is not haram to perform salat, but to delay performing qada salats.

One is sinful not because one performs a qada salat but because one did not perform that salat at its due time. One is not sinful as one performs a qada salat but sinful as one delays it without any reason. So is the case with gathering two fard salats together, that is, to skip a fard salat without an excuse and to perform it in the time of the following salat. What is a sin is not to do qada of it, but to skip it. It is fard to do qada of a salat that is not performed within its prescribed time.

It is makruh tahrimi, even haram, to perform Salat al-Asr at the time when it is quite close to the time for Salat al-Maghrib. In this example, it is not haram to perform salat, but what is haram is to delay it until that time. If one has not performed Salat al-Asr until the time when there is one minute before the time for Salat al-Maghrib starts, it is still fard to perform Salat al-Asr. However, one is sinful if one delays it until that time without an extreme necessity.